In the past, an image forming apparatus heats and fixes a toner after transferring the toner onto a sheet. After the heating and fixing, a conveying roller conveys the sheet to a paper discharge tray, a finisher, or the like. The temperature of the toner on the sheet immediately after being heated and fixed is high. Therefore, the sheet is not instantly cooled. The conveying roller conveys the sheet in the high-temperature state.
In general, the conveying roller includes, on a roller shaft, plural rubber rollers having width smaller than sheet width. The temperature of the rubber rollers is low. When the conveying roller conveys the sheet having the toner not cooled yet, the toner on the sheet comes into contact with the plural rubber rollers and the heat of the toner is deprived by the rubber rollers.
Therefore, a temperature difference occurs in the toner on the sheet between a portion in contact with the rubber rollers and a portion not in contact with the rubber rollers. In other words, a difference occurs in a way of cooling of the toner on the sheet. When the sheet is discharged and the toner is cooled, gloss unevenness occurs on the surface of the sheet. In particular, when an image is printed on, for example, glossy coated coat paper or waterproof paper like a color photograph, a phenomenon of the gloss unevenness conspicuously appears.